This research project is aimed at the identification of type, rate and severity of complications of prehospital cardio-pulmonary resuscitation. The study will describe specific complications of C.P.R. and examine their relationship with rescuer and rescue techniques, victim characteristics and circumstances of the acute event. All persons who undergo a sudden and unexpected collapse and who receive cardiac resuscitation are included in the study. Working with the Dade County Medical Examiner's Office, five Fire/Rescue systems and all the hospitals in the region with emergency facilities, data is collected on the patient and rescuers, as well as the rescue procedures undertaken on the scene and en route to the hospital. Autopsies and external examinations are performed on all non-survivors brought to the M.E.'s office. Emergency Department and in-patient records of all survivors are abstracted to identify the complications attributable to C.P.R. A major project objective is to make recommendations regarding prehospital C.P.R. training, equipmant and techniques designed to reduce the complications of C.P.R.